[23][24] Symonds became the Conservative Party's head of communications in 2018,[25] but left the position later that year,[16] taking up a job in public relations for the Oceana project.

[5] In 2007, aged 19, Symonds was driven home from a King's Road nightclub by taxi-driver John Worboys, who in 2009 was convicted of multiple sexual assaults on his passengers.

She later recalled Worboys offering her champagne and vodka,[2] which she believed was spiked and, after returning home, began "vomiting and laughing hysterically before passing out until 3pm the next day".

[30] Symonds was the youngest of Worboys's victims, and waived her anonymity to talk about her experiences and, later, to campaign against his early release, fundraising for a successful judicial review of the decision.

[32] She began an affair with British politician Boris Johnson, then Foreign Secretary, in 2018 while he was still married to his second wife, Marina Wheeler.

The following month, she was barred from entering the United States as her visa application was rejected due to a previous visit with her close friend Nimco Ali to Somaliland, which the US considers to be part of immigration-restricted Somalia.

[33] On 16 August 2019, she made her first public appearance since entering 10 Downing Street, when she addressed what she called the "gigantic" climate crisis.

[37] Symonds married Boris Johnson in secrecy on 29 May 2021 in a Catholic ceremony at Westminster Cathedral attended by thirty guests.

[47] Concerns over her influence on the prime minister were raised in January 2020, when it came to light that she had received briefs from animal rights activists just before the government pulled a planned cull of badgers in Derbyshire.

[48] An association representing farmers, the NFU, asserted that this meeting and her influence played a key role in the government ignoring scientific advice in favour of retaining the cull.

[48] She was also influential in making sure that Lee Cain did not get a job as the prime minister's chief of staff,[49] and urged Boris Johnson to fire environment secretary George Eustice from his role.

[56] Cummings later said in 2021 that Symonds acted "illegally" in awarding influential jobs to her friends, including press secretary Allegra Stratton.

[59] Journalist Sarah Vine, on the other hand, said that while it is easy to "blame the woman", the truth is "far more complicated", adding that Johnson's head did not deserve "to be on the block".